Flexible metallic tube.



No. 817,057. PATENTED APR. 3,1966.

E. T. GREENFIELD. FLEXIBLE METALLIC TUBE.

APPLICATION FILED OUT. 24,1904.

To all whom it maly concern:

Be it known that I, EDWIN GREENFIELD, a citizen of the United States, residingat' Monticello, county/0f Sullivan, and State of New York, have made a new and useful Invention in Flexible Metallic Tubes, of which:

PATENTOFFIOE.

EDWIN T. cannnrmhn,oniuo vrrontilo; NEW roux,

, y r FLEXIBLE-vMET Specification uofLetters wa A earances statute-190i. Serial No. 229,723.

lPate nted April 3, 1906.1

the following, is a specification.

My invention is directed particularly to improvementsin flexible tubes likethose disclosed in rior patents heretofore granted to me, and t e same will be fully understood by referring to the accompanying drawing, which is a part side elevational, part sectional, view of a flexible metallic tube embodying my improvement. The tubes is referred to, which are known widely in the art of flexible armored conduits, are made by theuse of the mechanism and by the practice of the method disclosed in United States Patents Nos.- 630,502 and 630,503, granted to me on the 8th day of August, 1899. In the manufacture of such tubes so long as the-same are of reasonably small diameters, not exceeding,

.say, one inch in internaldiameter, it is possible to construct the same with flexible convex and concave strips of comparatively thin metal, the practice ofthe' method referred to and the use of the machine constructing a tube which is reasonably flexible and with suflicient interlocking friction to prevent the .same from being drawn apart byordinary rBtIGSS or by bending. I have discovered, ll'iowever, that when tubes of much lar er internal diameter are required-such, or in stance, as armored hose tubesr-it becomes necessary to use metal strips of comparativc'ly much greater thickness to give to the completed tube the desired set, so that the spirals thereof will not unwind, this because of the fact that by reason of the increased diameter of the tubes there is less rigidity of the strips when formed in their interlocking relation, will be readily appreciatedby those skilled in the art ofworking metals It therefore became necessary to use metal strips of greater thickness for the purpose of effecting the desired set and stability of the parts; but the use of such strips of such increased thickness necessitated also the use of dies like those disclosed in the before-men-- tioned patents of heavier parts and also re quired the utilization of greater power in forcing the material therethrough,

The present invention has for its object, therefore, the construction of an improved flexible metal tube of relatively large internal diameter'and of thinner metal strips than was possible i when constructed upon" the mechanism and by the practice of the method before utilized, as described in the beforementionedpatents. l i i To this endlform a central convex corrugation upon each strip of metal, said corrugations being exteriorly and interiorly disposed upon the strips in interlocking relation in the direction of their lengths, as disclosed in the accompanyii'ig drawiir numerals 1 and, 3 represent the interlocking concave and convex strips, the strips 1 being provided with a centrally-disposed convex corru ation 2 andthe strips 3-with a correspon iugly-disposed convex corrugation 4, said strips being formed in interlocking relation in the manner disclosed in thebeforementioned patents, the feed-rolls, however, being obviouslyso constructed as to produce upon the strips the corrugations 2 :and 4, or, iffpr'eferred, these corrugations mi ht be effectedlbefore the strips are passed through the feed rolls. By the disposition of such corrugations in the manner described and shown an increased strength is given to the tube and increased rigidity, and this with a minimum amount of material.

I do not limit my improvement to its use with flexible tubes like that disclosed in the drawing, as obviously the same may be used in armoring cables in the manner disclosed in a prior patent, No. 616,612, granted to me on the 27th dayof December, 1898, or itmay v in which the be used in connection with armored hose in the same manner as disclosed in United States Patent No. 746,630, granted to me on the 8th day of December, 1003, the especial point of novelty in the invention consisting in giving material strength to the interlocking strips by-corrugating the same centrallyin the manner described and shown and this with a minimum amount of metal; nor do I limit my invention to a flexible tube made of two interlocking convex and concave strips each provided with a corrugation in the direction of its length, as shown in the accompanying drawing, as obviously a flexible tube might be made of a single strip of metal having a longitudinal corrugation and constructed in the manner disclosed in my previous patent, No. 030,503, above referred to, the strip being corrugated as it is given the tubular form or previously, if preferred. It is also obvious that more than one corrugation might be made 1n each strip instead of a single corru- IIO gation, such matters being a question of degree only.

Having thus described my invention, what I claim, and desire to secure by Letters Patent of the United States, is

1. A flexible tube constructed of spirally- Wound interlocking strips of metal, one of which is convex and the other concave in the direction of its length, and each having a central convex strengthening corrugation extendin also in the direction of its length, said strengt ening-corrugations being disposed in interlocking relation.

2. A flexible tube constructed of interlocking metal strips one of which is convex and the other concave and each of which is provided with a convex centrally-located corru gation extending in the direction of its length, said strips having a fixed set which prevents them from unwinding and the centrally-located corrugations being disposed in interlocking relation.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

EDWIN T. GREENFIELD.

Witnesses:

C. J. KINTNER, M. F. KEATING. 

